I think she is asking way too much money but... It sounds like this little girl is meant for you so I'd go for it. Three is a lot of work. I have 3 and would never get rid of any of them and I love them all but it's really more work than I wish I had. If you wanted to re-home your little boy, I really see nothing wrong with that. I know you'd find him a wonderful home and you could have the girl you've been wanting and the amount of dogs that your family is comfortable with. Good luck!
__________________
"If you have men who will exclude any of God’s creatures from the shelter of compassion and pity, you will have men who will deal likewise with their fellow men." — St. Francis of Assisi, 1181-1226